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Multimedia Displays M S E I

Blankenbach / www.displaylabor.de / Touch / SS 2014

Introduction

Display Measurements

Summary & Outlook

Overview

Some pictures etc. are

courtesy of the companies

named on the picture,

others from, e.g., SID, …

Displays (LCD, OLED, E-Paper)

3D, Touch, Systems & Interfaces

1


Blankenbach / www.displaylabor.de / Touch / SS 2014 2 2

• Introduction

• Touch Screen Technologies

Overview

• Application Issues

• Summary

Some slides are from Touch

Screen tutorials given by

3M, Fujitsu, Walker Mobile &

Elo TouchSystems



Touch Screens

Why - because it is in for CE since 2007!

Touch is not only technology – it is also user interface driven !



Touch Screen Basics

Finger input:

- simple, no device required, multi touch (gestures)

- but low “resolution”

Sylus input:

- simple, high

resolution (> 50 ppi)

- stylus required

- SW for text input



Touch Screens

• Easies many HMI concepts by direct input (command buttons etc.)

• Mature technologies available

• Allows easy input incl. characters and graphics e.g. smartphone

• Space saving compared to keyboard and mouse

Why ?

• Rise in some application system costs

• Reduced ambient light performance of display

• Inadequate performance of text input via stylus (is also an additional item !)

• Often more time consuming than keyboard and mouse

Why not ?



Professional Touch Screen Applications • Point of sale (POS) in restaurants, hospitality, post offices, …

• ATMs

• Industrial/process control

• Medical equipment

• Office equipment like copiers

• Retail

• Automotive: navigation, diagnostic systems

• Kiosks: Point of information (POI), merchandising, tourism & museums,

digital photo printing stations, …

• Ticketing & vending incl. transportation

• Gaming, amusement, …

• Telecommunication

• Internet terminals

• Outdoor: Gas pumps, store window applications, …



Touch Screen Cost Share

About the same price as for LCD !


Blankenbach / www.displaylabor.de / Touch / SS 2014 9

Touch about Half the Price of AMLCD @ NEW IPAD

iPad bill of materials (BOM; Source: IHS isuppli, March 2012)



• Introduction


Overview


• Summary



Display CL* T

G

a

p

G

a

p

TC IF SW

System

Display data

Touch Screen System

Display

Cover lens

Touch

Add-on Touch (not to scale,

avoid air gaps)

Resistive,

IR, SAW, …

Gap

PCap PCap

“Sensor

on Cover”

Integrated Touch

PCap

“Sensor

on Cell”

In-Cell

“Sensor

in Cell”

… includes

- Touch sensor (T)

- Touch controller (TC), interface (IF)

- Software (SW: driver, OS, …)

- …

Different ways to integrate a touch:



Touch Technologies 1/2

Criteria: - Display size,

- Touch object,

- Integration, …



Touch Technologies 2/2



Touch Screen System

…includes

- Touch sensor

- Touch controller, interface

- Software (driver, OS, …)



Projected Capacitive (V)

IPHONE Hardware



Projected Capacitive Cost Share

APPLE IPHONE integration

3$

3$

Integration 10$



Capacitive Overview

(no multi-touch)

Only small changes of capacity

are forced by finger etc.

sophisticated touch controller

and algorithms needed

Mainstream



Projected Capacitive

IPHONE HMI Examples




Principle: Electrical field changes due to influence of dielectric parameter

Push by smartphones & tablets (CE touch awareness)

Touch controller is mission critical




Screen

Principle

• A specially structured multi-layer

ITO-film is fully laminated to a

glass substrate.

• By the specially structured electrodes

an electric field will be „projected“

through the glass substrate.

• This electric field changes due to the

influence of a touch element (finger).

The dielectric parameter will change

and the controller (mission critical) can

calculate the position of this change.

• The touch finger does not need to

be conductive !



P-Cap Touch Screen Board

- Touch controller (TC)

- Interface (IF)

- Software (SW: driver, OS, …)

- Resolution, …



P-Cap Touch Signal Processing

- Control sensor electrodes to generate raw data

Noise avoidance via multiple techniques: Frequency Shifting, CDM, etc…

- Process data to convert to image data

- Derive and report data about finger touches (position, width, gestures)



• High resolution

• Multi-touch

• Fast response

• Good with finger, light touch

• Reliable & durable (protected sensor)

• High optical quality (plain glass)

• Unaffected by surface debris or contamination

Benefits

• Expensive

• Touch controllers are complex

• Stylus and gloves result in limited or no function

• Some EMI susceptibility

Issues




Analog Resistive

Leading technology

until ~ 2009.

Reason: APPLE‟s IPHONE

with multi touch and

superb ambient

light capabilities.



Analog Resistive

Principle

‚Short„

To touch

controller

4, 5 & 8 wire technology

Air gap poor ambient light performance Touch screen board also needed



Analog Resistive (III)

Spacer

visible

In-flight entertainment system



Analog Resistive (IV)

x

y

2

1

R

Rx

4

3

R

Ry

‚Calculation„ of touch impact position

Multi touch ???

http://upload.wikimedia.org/wikipedia/de/8/81/Touchscreen.png



Resistive Touch Screen Board



Analog Resistive

• Wide-spread technology

• Low cost

• High resolution

• Insensitive to EMI

• No special equipment necessary, good with finger, glove, …

• Highly resistant to screen contaminates

• Sealability

• Low power consumption

Benefits

• No multi-touch (except for some special solutions)

• Relative high touch force

• Poor optical transmission (performance)

• Poor durability

Issues



Comparison

Technology Multi-

touch Resolution

Form factor

(bezel) Cost

Resistive No 100+ dpi,

any object ~ 5mm Low

Projected

Capacitive Yes

10 dpi - only

works with a

human finger

~ 1mm High

- All touch screens reduce clarity and enhance reflectivity of the display

- All touch screens rise power consumption:

LCD – Backlight or emissive luminance must be enhanced



Mobile Infrared Touch

Source: Walker, public and private



LCD In-Cell

• Visible in-cell sensor development stopped in industry

• IR- in-cell difficult to manage due to ambient IR

• In-cell pressure capacitive in SAMSUNG digital camera

but no cover glass possible (not a good idea)

• In-cell self capacitance touch not feasible due to cover glass

In-cell touch approaches show limited potential

Source: Walker, public and private



In-Cell Touch

In-cell light sensors

capture position like

a flat camera

Multi touch !



Source: Mackey, Synaptics

In - Cell Touch

There are rumors about in-cell touch

display from SHARP for IPHONE V



Camera Based



Radar Touch

• Excellent for large sized screens

• Gesture OK

• Lacks of multi touch by

geometric blocking



• Introduction


Overview


• Summary



Touch Screens & System • Total cost of ownership: Consider initial purchase price plus long-term

costs including operation and maintenance

• Accepted input devices

Is it important that the application work with a finger, a gloved finger, a

metal stylus, a nonconductive stylus, a credit card, and/or a long fingernail?

• Durability: How harsh is the intended environment?

Will the system be used in the public sector (vandal considerations)?

• Image quality of the underlying display: Are clarity, brightness and

readability of the display important to the application?

• Sealability and chemical resistance: Is the screen/device likely to be

subjected to spills and/or cleaning with harsh chemicals?

• Reliability: What is the impact of any downtime for repair?



Touch Tasks

Acquire

• Touch position

• Number of touches (fingers)

• Gestures, …

Screen

“here”

Equipment etc. needed:

• Software to visualize GUI etc

and outputs (to e.g. file) touch

parameters like co-ordinates

• High speed camera for touch

events lag measurements or

equipment similar to response

time measurements

• Touch objects

• …



Touch TOUCH POSITION ACCURACY

• Simple test for controls etc.

• 5 or more point can be used,

“same” as uniformity

• Touch co-ordinates should

be located in the center of the

circles

• Use software which shows

buttons, circles, … and outputs

the touch co-ordinates X/Y

• To be judged: Co-ordinate in the

center of control if touched there

Source: IDMS

W/2

H/2

H/10

W/10 W/4 ; H/4



Touch LINEAR ACCURACY

• Deviations from straight line,

usually 4

• Move touch object along ruler

• Use “normal” speed

• Software stores touch co-ordinates

• Report on deviations:

- Average deviation (difference)

- Maximum difference

• To be defined:

Acceptable deviations

W/2

H/2

Reference

by ruler

Linear regression (tendency)

Acquired

Average

deviation



Touch REACTION TIME: LATENCY OF A SINGLE TOUCH

• Measure how fast the whole system reacts on a touch event

• This duration is influenced by many parameters like

response time of touch, touch signal processing, touch interface,

operating system response time, …

Source: IDMS



Touch REACTION TIME: LATENCY OF A LATERAL MOTION

• Measure the latency time between the input and the system reaction

• Similar measurement: Fastest movement of touch object without noticeable

latency between touch position and system reaction like curve

• This time is influenced by many parameters like response time of touch,

touch signal processing, touch interface, operating system response time, …

Source: IDMS



Touch Evaluation Summary

• Typical touch measurements are:

- Position

- Number of touch objects

- Accuracy of lines

- Speed

• There are a lot more like sensitivity to touch objects (like gloves),

cover lens thickness, dust and dirt on touch screen

• Especially “speed” (and gesture) strongly depends on system

reaction time where touch screen parameters are only a few

among many influencing topics.



Touch Screens & Ambient Light

Optical bonding !



Touch Issues

• Touch can damage the screen by pressure (e.g. LCD spacer)

• LCD touch can result in (temporal) image degradation (picture)

• Touch hinds objects on screen large buttons



Fingerprints

Source: DAIKIN



Touch Screen Overview (selected technologies and topics)

Resistive Capacitive IR

(e-reader) In - Cell

Multi touch - ++ + ++

Outdoor appl. - + + ++

Touch object ++ - + ++

Flush surface + ++ - ++

Integration Add on Add on,

in-cell Add on

Panel

maker

Size < 10” ++ ++ + ++

10” … 30” + + ++ ++

> 30” o o ++ ++



Touch Technology Comparison

Source: M. Jones



• Introduction


Overview


• Summary



Interaction Approaches Beside Touch, Mouse, Keyboard

Source: Display Search 2012



Stylus & “Mouse over”

Source: Walker Mobile

SID 2012



From Touch to 3D Gesture and Position

60

How many alarm clocks are falling down

each morning because a “touch” is

required to stop alarm sound ?

Touchless gestures are more suitable

but only a well-defined gesture reduces

“failures” e.g. “stop” vs. “snooze”.

Touchless would increase

safety while controlling

sliding sunroof as no

“touch” at a certain position (button) is required.

Sources: MICROCHIP



Comparison Touch Touchless

Resistive PCap Camera Optical Cap

Easy of use easy easy difficult easy easy

Functionality low high medium medium medium

Position detection high high low medium medium

Multi touch no yes 2 hands no no

Gestures basic advanced advanced basic advanced

HW requirement low medium high medium low

Implementation simple challenging challenging medium simple

Power consumption low low high medium low

61

Human Machine Interaction Approaches H

e

r

e



MICROCHIP GestIC for “Touchless Touch” & 3D Gestures

62

MICROCHIP GestIC

µC, gesture visualization

GestIC

Electrodes

and connections

LCD with driver

Applications:

- Touchless 3D control

- Wake up on approach

Merits:

Hygienic, no contamination, even for

simple devices without a display

K. Blankenbach, A. Delovski: Novel Gesture and Touch System with Transparent and

Curved Electrodes Enables New Computer-Human Interactions, International Conf-

erence on Advances in Computer-Human Interactions (ACHI 2014), Barcelona, 3/2014



Touchless Application: Shopping Windows

63

• (Optical) camera may cause fear of being captured in “crazy clips” in internet!

• (Optical) camera has often difficulties dealing with all lighting situations.

• Camera systems are expensive in complex to integrate.

3D gesture with low cost transparent electrodes will overcome these issues

however electrode size has to be increased or “small operating pad”.



Summary

• Touch screens have many advantages like HMI

• Mature technologies available

• Integration needs some expertise incl. ambient light

• Not every touch technology is suitable for dedicated applications

Touch has many benefits

but need some system considerations



Case Study: Outdoor Kiosk

Topic Requirement PCAP Resistive

Size

Touch object

Multi touch

Ambient light

Vandalism proof



Summary



What Touch Screen Technology Is It ? (I)

• If it responds, it‟s either infrared or optical

- Resistive needs pressure

- Surface & projected capacitive need a finger

- Surface acoustic wave needs a sound-absorbing contact

- APR/DST (bending wave) needs a firmer touch

• Block the corners of the screen with something opaque

- If it still responds to a touch away from the corners, it‟s infrared

(IR transceivers are distributed all around the periphery)

- If it stops responding, it‟s optical

(imaging cameras are located in the corners)

Brush the screen very lightly with Kleenex



What Touch Screen Technology Is It ? (II)

• If it didn‟t respond, poke it with a toothpick

- If it responds, it‟s resistive or APR/DST (bending wave)

- Surface & projected capacitive need a finger


- Check to see if the surface moves ever so slightly when you

poke it with the toothpick (watch a reflection of a light source

on the surface of the screen and try several locations)

- If the surface moves, it‟s resistive (the surface is PET)

- If the surface doesn‟t move, it‟s APR/DST (bending wave)

the surface is glass




What Touch Screen Technology Is It ? (III)

If it didn‟t respond, touch it with a pencil eraser

- If it responds, it‟s surface acoustic wave


- If it doesn‟t respond, it‟s either surface or projected capacitive

- Surface capacitive and projected-capacitive need a finger

- Check for faintly visible straight or jagged lines in a repeating

pattern in the darkest areas of the screen (the lines are most

visible when the screen is powered off and you‟re looking at

the surface using reflected light)

- If you see lines, it‟s projected capacitive

(you‟re seeing the transparent conductors on the sensor)

- If you don‟t see any lines, it‟s surface capacitive


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